1. Field of the Invention
The present invention relates generally to a vehicle seat assembly, and more particularly to a vehicle seat assembly having a field effect sensor for detecting the position of the vehicle seat assembly.
2. Description of the Related Art
Automotive vehicles employ seating systems that accommodate the passengers of the vehicle. The seating systems include restraint systems that are calculated to restrain and protect the occupants in the event of a collision. The primary restraint system commonly employed in most vehicles today is the seatbelt. Seatbelts usually include a lap belt and a shoulder belt extending diagonally across the occupant's torso from one end of the lap belt to a mounting structure located proximate to the occupant's opposite shoulder.
In addition, automotive vehicles may include supplemental restraint systems. The most common supplemental restraint system employed in automotive vehicles today is the inflatable airbag. In the event of a collision, the airbags are deployed as an additional means of restraining and protecting the occupants of the vehicle.
Vehicle seats are typically linearly adjustable toward and away from the dashboard. Originally, the primary and supplemental restraint systems were designed to operate in the same manner during a vehicular collision regardless of the linear seat position relative to the dashboard. For example, some airbag systems deploy with the same speed and force regardless of the seat position. However, in some instances, the speed and force of the deploying airbag is too great for persons sitting close to the dashboard, and injury can result.
Partially in response to this need, vehicle safety systems have been proposed with a means of detecting the seat position and communicating the detected position to a controller that controls the primary and/or supplemental restraint systems accordingly. Many of these systems incorporate a Hall effect sensor and a magnet emitting a magnetic field. Generally speaking, the Hall effect sensor of these systems detects changes in magnetic flux caused when the seat moves and the system correlates this change to a certain seat position. One such safety system is disclosed in U.S. Pat. No. 6,095,555 to Becker et al. In the Becker et al. system, a Hall effect sensor and a magnet are fixed to a vehicle interior, adjacent a vehicle seat. Movement of the vehicle seat past a predetermined forward position causes a portion of the seat to enter the magnetic field created by the magnet, thereby changing the magnetic flux. Upon detecting this change, the Hall effect sensor sends a signal to a controller, which alters or prevents the actuation of a restraint device. More specifically, the device disclosed in the Becker et al. '555 patent can be used to prevent an airbag from deploying or can suppress the inflation of an airbag if the device detects that the seat is less than a minimum distance from the stowed airbag and injury might otherwise occur to the occupant.
While the Becker et al. and similar Hall effect systems can alter or prevent actuation of a vehicle restraint system depending on seat position, there remain certain drawbacks associated with these systems. Particularly, relative positioning between the Hall effect sensor and the magnet in these systems is especially important, typically requiring assembly within tight tolerances, and this can increase manufacturing time. Also, these seat positioning detection systems can be designed for a vehicle with one set of interior dimensions, but incorporating that same system into a different vehicle with different interior dimensions will usually require a time consuming and costly re-design of the system. This is because the relative positioning between the Hall effect sensor and the magnet will likely have to be re-designed according to the different interior dimensions, such as different distances between the seat and the steering wheel, dashboard, etc.
Therefore, there is an ongoing need in the art for a vehicle seat assembly that has a seat position detecting system that can be more easily assembled and that can be more easily adapted for vehicles with differing interior dimensions.